Template-based multiwalled TiO2/iron oxides nanotubes: Structure and magnetic properties

Abstract

Double- and triple-walled TiO2/iron oxide nanotubes with well defined interfaces have been produced in nanoporous alumina templates using atomic layer deposition method. The structural properties of each individual layer are found to be dependent on the deposition temperatures. The outer layers of TiO2 are polycrystalline and consist of a phase mixture of anatase and rutile, while the inner TiO2 layers grown at lower temperature are amorphous. The iron oxide layers consist of pure hematite when deposited at 500 °C, while a phase mixture of hematite and magnetite was obtained at 400 °C. The magnetization measurements reveal that the studied nanotubes exhibit weak ferromagnetic behavior and magnetic anisotropy with an easy axis perpendicular to the tube axis.